man rtcwake


-m, --mode mode
              Go into the given standby state.  Valid values for mode are:

                     ACPI state S1.  This state offers minimal, though real, power savings,  while  providing  a
                     very low-latency transition back to a working system.  This is the default mode.

              freeze The processes are frozen, all the devices are suspended and all the processors idled.  This
                     state is a general state that does not need any platform-specific  support,  but  it  saves
                     less power than Suspend-to-RAM, because the system is still in a running state.  (Available
                     since Linux 3.9.)

              mem    ACPI state S3 (Suspend-to-RAM).  This state offers significant power savings as  everything
                     in  the  system  is put into a low-power state, except for memory, which is placed in self-
                     refresh mode to retain its contents.

              disk   ACPI state S4 (Suspend-to-disk).  This state offers the greatest power savings, and can  be
                     used  even  in  the absence of low-level platform support for power management.  This state
                     operates similarly to Suspend-to-RAM, but includes a final step of writing memory  contents
                     to disk.

              off    ACPI  state  S5 (Poweroff).  This is done by calling '/sbin/shutdown'.  Not officially sup‐
                     ported by ACPI, but it usually works.

              no     Don't suspend, only set the RTC wakeup time.

              on     Don't suspend, but read the RTC device until an alarm time appears.  This  mode  is  useful
                     for debugging.


sudo crontab -e

30 23 * * * sudo rtcwake -l -s 3600 -m mem